Tesla wasn’t shy about advertising its launch of a Tesla Roadster on board a Falcon Heavy rocket, on Tuesday. But the company was less vocal about that Roadster’s secret cargo: a tiny optical disc, known as an Arch (pronounced “ark”). Theoretically, this format of disc can hold 360TB, and the one aboard the launched car contains Asimov’s Foundation book trilogy.

Unlike traditional optical discs, according to the Arch Mission’s press release, this Arch disc is “written by a femtosecond laser on quartz silica glass” and its data is “encoded digitally as 20nm gratings, formed by plasma disruptions from the laser pulses.”

“Each dot encodes 8 bits in 5 dimensions of light,” the group states. “Theoretical capacity is 360TB per disk, and the Archs are stable for 14B+ years. No other medium offers this kind of data capacity and durability.”

However, the ambitious group was not immediately able to explain exactly how this data could be read by other humans who don’t have specialized hardware to access the data, much less alien civilizations in the future.

“A message to future humans”

On its website, the Arch Mission Foundation explains its hope that future recipients of the Arch will somehow be able to decode the device and build the necessary computer to read it. (The Foundation does not explain precisely how other civilizations will be able to understand any of Earth’s written languages, but it plans on making the information as easy as possible to decode.)

“Beyond the visual layer, we also are encoding higher resolution data for audiences with access to lasers and computer-based digital technology,” the group writes. “Here we can store truly big datasets, but it is more difficult for a recipient to access this data. To facilitate this, on the visual layers above this layer, we will include instructions for how to access and decode digital data, and if necessary how to build a computer and laser to do so.”

The effort is vaguely reminiscent of the 1977 Voyager 1 mission, which contained a visual and audio representation of human civilization on Carl Sagan’s famed “Golden Record.”

The Arch Mission Foundation non-profit organization plans to launch many more Archs in the coming years.

Nova Spivack, co-founder of Arch Mission, told Ars that his group plans on sending up more quartz discs and other types of storage devices in various media each time a spacecraft launches.

“We are trying to send a message to future humans,” he said. “We don’t have to teach them physics or teach them math. We want to design objects for those locations; we want to design objects that are designed purposefully for data miners. In that scenario you want to give them a lot of data and help them apply machine learning to figure out what’s in the data. The biggest challenge isn’t ‘Can they get the data?’ The question is, ‘Will they understand what it all means?'”